This type of electrical power supply for an electrically-propelled vehicle from a distributor arm and a conductor rail carried by the vehicle has many advantages, of which one is a saving on power cable suspended along the road, and on posts, and the fact that you only need the minimal infrastructures that allow this type of power supply, notably, for urban transport.
These advantages and benefits are lessened by the difficulties inherent in the making of contact of the power supply arm with the conductor rail carried by the vehicle.
This is because, for electrical and mechanical reasons, the making of contact of the conducting part used as shoegear of the distributor arm with the conductor rail present on the roof or side of the vehicle must be firm and without bounces, while being gentle and dampened without shock. Because the vehicle arrives under the arm at a certain speed, the advance of the ramp tends to raise it. Therefore, the fall of the arm has to be dampened, to prevent the shoegear from breaking on making contact with the conductor rail.
Similarly, once electrical contact has been established, the shoegear must not disconnect from the power supply rail, or else there will be electrical arcs that can damage it. Often, the power supply rail is not perfectly rectilinear, and the vehicle can also bounce due to rolling on the road surface. To have the best-possible electrical contact, the arm must oscillate with a dampened movement that prevents it from disconnecting in an undesired manner.
One also has to properly master the shoegear's bearing force on the conductor rail. Thus, in addition to a damper, the invention also makes provision for a load compensation spring.
WO 2011/079215, too, covers an electrical power supply unit for vehicles including lateral shoegears between which a conductor rail of the vehicle engages. These lateral shoegears have deflecting portions at the front, so as to facilitate engagement of the conductor rail. The desired height of the lateral shoegears in relation to the conductor rail is obtained and maintained by a wheel, for example, that is integral with the mounting of the lateral shoegears and that comes into contact with the roof of the vehicle. The movement of the wheel on the roof of the vehicle ensures optimal heightwise positioning of the lateral shoegears in relation to the conductor rail. This is because the wheel has to roll the whole time on the roof, throughout the duration of electrical contact between the shoegears and the conductor rail. It is sought to maintain and carry the shoegears at a constant height in relation to the roof of the vehicle, to prevent damaging wear to the underneath of the said shoegears, due to friction on the roof. Such an implementation, which is adapted specifically for the lateral shoegears, does not prevent or attenuate shocks that occur during the electrical contact between the said shoegears and the conductor rail. These shocks are non-negligible, especially for a vehicle arriving at the power supply station with a speed that can be as high as 40 kph or 50 kph.